303P Switching Relay - 3 Zones w/ Priority
Hover image to zoom

303P Switching Relay - 3 Zones w/ Priority

303P Switching Relay - 3 Zones w/ Priority
Hover image to zoom
$175.29 each
In Stock
In Stock
Get 10 Wed, Mar 6
Free Shipping This item ships free
Easy Returns No restocking fee for 90 days

Product Highlights

Number of Zones icon


The Switching Relay 303P connects up to three thermostats and operates circulators to provide heating to a zoned hydronic heating system. Zone 1 has optional priority over zones 2 and 3 and can be used to provide heat to an indirect domestic hot water tank. The 303P includes optional exercising to prevent circulator seizure when not in use, and optional post purge operation of the last operating zone to maximize energy savings. The 303P provides a RoomResponse™ signal to modulating-condensing boilers to optimize comfort while improving boiler efficiency.

  • Away signal shared between tekmar thermostats
  • CSA approved
  • Compatible with all low voltage thermostats
  • Four ground screws
  • Fuses protect transformers and pumps
  • LED for each zone, priority, end switch and RoomResponseTM
  • Post purge
  • Priority override
  • Pump exercising
  • RoomResponseTM signal
  • Top, bottom and back conduit knockouts
  • Two spare fuses included
  • Unlimited zone expansion
  • Zone priority
  • Enclosure - Cover: ABS plastic, Base: galvanized steel, NEMA type 1
  • Approvals - CSA C US
  • Ambient conditions - Indoor use only, 32 to 122°F (0 to 50°C), RH 90% non-condensing
  • Power supply - 115 V (ac) ±10%, 60 Hz, 16 A
  • Transformer - 40 VA, expandable to 80 VA with additional transformer M3069 (sold separately)
  • Fuses - T5A 250 V slow blow, two spare fuses included
  • Pump relays - 115 V (ac), 5 A, 1/3 hp, 16 A combined
  • Boiler XX end switch - 24 V (ac), 5 A
  • DHW end switch - 24 V (ac), 5 A
  • Mod boiler output - 0-10 V (dc) 500 ohm min load impedance / 4-20 mA 1 k ohm max load impedance


Product Type:


Number of Zones:


Power Supply:


Help Face


Speak with a real person who will go out of the way to help!
Call or text 888-757-4774

Free Shipping
On orders over $99
We offer flexible shipping and scheduling options, up-to-date delivery estimates, and free ground shipping on any order over $99 to make sure your order gets to you on-time, for less.
Shipping Policy
Easy Returns
Returning items is as simple as 1-2-3
Ordered the wrong product? Item damaged in transit? Our 3-step process makes returning products easy – even up to a year after purchase – with no restocking fees on returns made within 90 days.
Return Policy